Left: A Merlot grapevine shows redleaf symptoms on mature leaves in the lower portions of the canopy. Symptoms are easily confused with grapevine leafroll disease. Right: Cabernet Franc clusters from a single vine show infection on the left, nonsymptomatic cluster on the right. A new disease that threatens the health of grapevines nationwide highlights the need for stronger clean plant campaigns. The disease, first reported in a Napa Valley vineyard in 2008, has been identified in infected vines in the top three U.S. grape growing regions of California, Washington, and New York, as well as a few other East Coast […]